1. Field of the Invention
The invention relates generally to a communications system that communicate data over narrow or limited bandwidth medium. More particularly, the invention relates to a method and apparatus for transmission of video over narrow-band transmission channels, such as plain old telephone system (POTS) lines.
II. Description of the Related Art
Video telephones have existed within the marketplace for several years with little commercial success. The lack of success of videophones is attributable in part to the fact that they do not work very well. It has been problematic to transmit sound and video of acceptable quality across existing phone lines.
Some available video conferencing systems produce acceptable video and audio quality, and have met with some commercial success. Those video conferencing systems depend on wide bandwidth communication connections such as leased lines, ISDN (Integrated Services Digital Network), DSL (Digital Subscriber Lines) and the like. The high bandwidth is necessary to produce acceptable audio and video quality.
The available bandwidth on standard telephone lines has been too low to support industry standard 30 frames per second video. Currently, using compression, the best performance obtainable on standard U.S. phone lines is approximately 15 video frames per second in one direction. Because 15 video frames per second is less than the persistence of the human eye, which is generally about 24 frames per second, the 15 video frames per second results in a jerky unacceptable video quality. Even with expensive compression hardware, the quality of the resultant video may be unacceptable.
There is therefore a need for video communication systems, which do not depend on expensive compression hardware and yet yield an acceptable video display when transmitted bi-directionally across standard analog phone lines.
The invention provides an apparatus for creating at least one intermediate image frame based on at least two image frames in a video communications system. In one embodiment, the apparatus comprises a video device that is configured to capture a first image frame of an object, and further configured to capture a second image frame of the object after a defined period of time from the time the first image frame is captured. The apparatus further comprises a memory, electrically connected to the video device, the memory being configured to store pixel information related to the first and second image frames. The apparatus further comprises a processor, electrically connected to the memory, that is configured to identify a portion of the second image frame, provided that the identified portion was changed during the period of time. The processor is further configured to determine a location of an intermediate image portion based on at least the average respective locations of the identified portion and its corresponding portion in the first frame.
In another embodiment, the apparatus comprises first means for capturing a first image frame of an object. The apparatus further comprises second means for capturing a second image frame of the object after a defined period of time from the time the first image frame is captured. The apparatus further comprises means for identifying a portion of the second image frame, provided that the identified portion was changed during the period of time. The apparatus further comprises means for determining a location of an intermediate image portion based on at least the average respective locations of the identified portion and its corresponding portion in the first frame.
In another embodiment, the invention provides a method of creating at least one intermediate image frame based on at least two image frames in a video communications system. The method comprises capturing a first image frame of an object, and capturing a second image frame of the object after a defined period of time from the time the first image frame is captured. The method further comprises identifying a portion of the second image frame, provided that the identified portion was changed during the period of time. The method further comprises determining a location of an intermediate image portion based on at least the average respective locations of the identified portion and its corresponding portion in the first frame.